Process for electrolytically precipitating metals.



UNITED STATlEd PATENT GEORGE C. WESTBY, OF LUDWIG, NEVADA, ASSIGNOR TO WESTERN PROCESS COMPANY, A CORPORATION OF MAINE.

PROCESS FOR ELECTROLYTICALLY PRECIPITATING METALS.

We Drawing.

cipitated from solutions containing the,

same.

The precipitation of metals in electrolytic processes, such as the precipitation of copper from copper sulfate solutions, by means of insoluble anodes, involves either the development of voltages much beyond the theoretical, with low current and energy ei'licieneies, or the use of complicated cells,

as in the Siemens-Halsk process. Low current efficiency is generally attributed to the solvent action of ferric sulfate, produced by the action of a current on the copper cathode, and low energy ciiiciency is due both to the low current cfliciency and the high voltage required to overcome the resistance of the electrolytdcontacts, back electric motive force, etc.

The object of the invention is to overcome the foregoing diflicultics by employing a semi-soluble anode, Which will tend to exert a strong reducing action. thereby preventing the formation of ferric sulfate, and thus increase the current efficiencies, While at the same time causing a drop in the voltage required, both by initiating a tendency for the development of a current in the same direction as the main current, and by increased conductivity of the anode.

The invention will be hereinafter fully set forth and particularly pointed out in the claims.

In the practice of the invention, the anode employed is preferably composed of iron, which ordinarily contains small amounts'of silicon and carbon. The means employed to prevent rapid solution is an application of the principle best illustrated by the fact that copper cannot be readily precipitated on iron from a solution heavily charged with ferrous sulfate by replacement. In pracice also, a film of carbon and silicious mat- Specification of Letters Patent.

Patented. July a, ram.

Application filed March 21, 1916. Serial No. 85,575.

ter is formed on the iron anode, thereby preventing rapid decomposition. It has been established by experiment that if the solution carries 6% Iof iron as ferrous sulfate at F. rapid corrosion of the iron is prevented and that from this point on the acidity begins to-increase with the decrease of copper content. It has also been found that the use of solutions which have been in contact with sulfurous gases also increases the energy efiiciency.

In practice the solutions employed are ob taincd by bringing roasted or oxidized ores into contact with hot sulfurous fumes containing both sulfur dioxid and sulfur trioxid from the decomposition of sulfates or sulfids in a roasting furnace. This solution, charged with S0, showing an equivalent acidity of approximately 1.5% to 2% sulfuric acid and laden with ferrous material derived from precipitation boxes, (following the electrolytic treatment, or arising from solution of iron fl'OlllytllO ore), is caused to How through a lofng ilun'ie in which the electrodes are placed paralleling the flumc. lVhile the current is being ap plied an electrolytic action is set up sullicicnt to decompose a portion of the anode. thereby forming additional ferrous sulfate in the solution, and exerting a strong reducing action on such ferric sulfate as might form,

thereby increasing the current ellici ncies and also resulting in a drop of the voltage required.

It will be understood that while an iron anode has been described in connection with a solution charged with ferrous sulfate. the

invention is not limited to this one metal. For instance, a Zinc anode may be employed in av solution of zinc sulfate and it is obvious that other metals might be employed in a solution containing the sulfate of the metal employed. Either or both electrodes may be caused to rotate.

The electrode is rotated in order that a much higher current density may be used than in the case of a stationary electrode. The value of our particular device is that in the rotation of the disk, the electrolytic gases are brought out into the air, so that they can escape freely.

The removal of the gases reduces to a minimum back electromotive force.

Having thus fully described my invention what I claim as new and desire to secure by Letters Patent is:

1. An improved method of electrolytic precipitation which comprises employing an iron anode in an acid solution heavily charged initially with ferrous sulfate and containing varying amounts of sulfur dioXid and copper sulfate.

2. An improved method of electrolytic precipitation which comprises employing a slowly soluble anode in a solution heavily charged initially with a sulfate of the metal of which the anode is composed, said solution containing varying amounts of sulfur vdioxid and copper sulfate in addition thereto. 3. An improved method of electrolysis employing an iron anode in a slightly acid solution heavily charged initially with ferrous sulfate and containing varying amounts of sulfur dioxid and copper sulfate wherein either or both electrodes are caused to rotate.

In testimony whereof I have signed my name in this specification.

GEORGE c. WESTBY.

Copies oi this patent may be obtained for five cents each, by addressing the "Commissioner or Patents, Washington, I). C. 

